Astronomy Picture of the Day

Explanation: Earth is not alone. It orbits the Sun with a small companion: Asteroid 3753. First discovered in 1986 and designated 1986 OT, this five kilometre rock was recently found to orbit the Sun while executing a strange dance with the Earth. A portion of the asteroid's complex orbit is shown above. As the Earth orbits once, Asteroid 3753 follows the yellow line - while also orbiting the Sun. Each time around, however, the yellow kidney-bean traced by Asteroid 3753 shifts slightly - eventually going from trailing the Earth to leading the Earth. Every 385 years the cycle repeats. Because the plane of 3753's orbit is tilted when compared to the Earth's orbit, the two will never collide. In autumn 1997, Asteroid 3753 will pass below the Earth's South Pole at about 100 times the distance to the Moon. It will, however, be very faint - about 15th magnitude - 10,000 times fainter than the dimmest star without a telescope. Suggestions are being taken for a good name for this asteroid.